Final test: Observability: metrics, alerts, logs

Read the output

Which process is tied to the 502 answers?

$ sudo grep '" 502 ' /var/log/nginx/access.log
::1 - - [22/Oct/2026:04:53:28 +0000] "GET /orders/export HTTP/1.1" 502 166
::1 - - [22/Oct/2026:04:53:29 +0000] "GET /orders HTTP/1.1" 502 166
$ sudo journalctl -k | grep 'Killed process'
Oct 22 04:53:28 ubuntu kernel: Memory cgroup out of memory: Killed process 1074 (python3)
Oct 22 04:53:35 ubuntu kernel: Memory cgroup out of memory: Killed process 1102 (python3)

• A Neither — nginx answers 502, the application has nothing to do with it.
• B 1074
• C 1102 — it was ended last.
• D Both: each kill produced its own 502s.